According to Politico, a group of Republican senators gave Iranian leaders — and the president — a refresher on the constitutional balance of power.

In a highly unusual move, a group of 47 Republicans in the upper chamber has written to Iran’s top leaders to let them know that any nuclear deal they reach with the United States would be “nothing more than an executive agreement.”

Freshman Sen. Tom Cotton (R-Ark.) organized the letter, which features signatures from top Republican Senate leadership and potential presidential candidates such as Sens. Marco Rubio of Florida, Ted Cruz of Texas and Rand Paul of Kentucky. Democrats blasted the letter, with Minority Whip Dick Durbin calling it a “cynical effort” that lays bare partisan rancor for the world to see.”